18909219 has 16 divisors (see below), whose sum is σ = 30509568. Its totient is φ = 10169472.

The previous prime is 18909173. The next prime is 18909221. The reversal of 18909219 is 91290981.

It is a happy number.

It is not a de Polignac number, because 18909219 - 2⁷ = 18909091 is a prime.

It is a super-2 number, since 2×18909219² = 715117126379922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18909229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26127 + ... + 26840.

It is an arithmetic number, because the mean of its divisors is an integer number (1906848).

Almost surely, 2^18909219 is an apocalyptic number.

18909219 is a deficient number, since it is larger than the sum of its proper divisors (11600349).

18909219 is a wasteful number, since it uses less digits than its factorization.

18909219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52994.

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 18909219 is about 4348.4731803243. The cubic root of 18909219 is about 266.4145034669.

The spelling of 18909219 in words is "eighteen million, nine hundred nine thousand, two hundred nineteen".